Tensioning device



Dec. 20, 1955 c. H. NORDELL TENSIONING DEVICE Filed March 26, 1954 JQW United States Patent Ofiice 2,727,627 Patented Dec. 20, 1955 TENSIONING DEVICE Carl H. Nordell, Palm Springs, Calif. Application March 26, 1954, Serial No. 418,944

Claims. (Cl; 209--394) This invention relates to a tensioning device, and is particularly concerned with means for holding flat metal strips in taut condition.

Although the invention will be described as specifically related to a screen having a plurality of flexible, flat metal ribbon screen bars it will be obvious that the tensioning means may be used for holding any non-rigid strips or bars taut, in any desired environment.

The tensioning device is particularly advantageous in connection with strips or wires that are subjected to forces tending to flex or distort them. In the preferred form of the invention each strip is held separately so that the strips may be flexed individually without affecting the taut condition of other strips not subjected to the specific force tending to flex one or more of the strips at any instant. As soon as such force is removed the strip or strips affected are immediately restored to their normal taut condition. A single tensioning element might be applied to a plurality of strips, but the flexing of one strip would cause every other strip held by the same tensioning element to be loosened temporarily, with possible interference to the proper functioning of the strips.

In the illustrated embodiment of the invention the strips are held rigidly at one end and are secured to individual tensioning elements at the other end. If desired, tensioning elements may be secured to both ends of the strips, but the structure having tensioning elements at only one end of the strips has been found to be sufiicient.

The structure by means of which the above and other advantages of the invention are attained will be described in the following specification, taken in conjunction with the accompanying drawing, showing a preferred illustrative embodiment of the invention, in which:

Fig. 1 is a perspective view of a screen in which the tensioning device is embodied;

Fig. 2 is a fragmentary cross sectional view through one end of the screen;

Fig. 3 is a fragmentary end elevation; and

Fig. 4 is a detail perspective view of one of the tensioning springs and the end of a ribbon screen bar in disassembled relationship.

In the drawings, the reference numeral 2 indicates a pair of channel members supported in inclined position on a pair of standards 3. A screen frame 4 is supported in the channel members. A cylinder 5 is rotatably mounted in the channel members adjacent the upper end of the screen. The cylinder is provided with a plurality of laterally projecting teeth which engage solids, intercepted by the screen and moved 01f the face of the screen to the cylinder by any suitable means, and transfer them to an area adjacent a comb 7 also mounted in the channel members. The comb is provided with notches 8, and the solids which are engaged simultaneously by the teeth and the edges of the comb defining the notches are comminuted by the interaction of the teeth and notches.

The comminuting device does not constitute any part of the present invention and is shown merely as part of the environment in which the tensioning device is used. The comminuting device is fully described and claimed in my copending application Serial No. 424,014, filed April 19, 1954.

The screen includes a plurality of flexible flat metal ribbons 9 which constitute the screen bars and are preferably rigidly secured at one end to frame 4. Ribbons 9 extend longitudinally of the frame in parallel relationship with each ribbon disposed edgewise. A bracket 10 extending transversely of the screen below ribbons 9 has its ends supported in said channel members adjacent the upper end of the screen. Bracket 10 has a rib 11 projecting rearwardly and terminating in a plane spaced a short distance forwardly of the ends of ribbonsv 9. Although it is preferable to have rib 11 integral with bracket 10, it may be formed as a separate member and secured to the bracket, or to the channel rearwardly of the bracket, in any suitable manner. A guide member 12 having its front edge 13 extending over the upper edge of bracket 10 extends upwardly over the ribbons and downwardly past the upper ends of the ribbons to guide the solids moved ofi the screen into engagement with cylinder 5. The guide member is provided with a plurality of slots 14 through each of which one of the ribbons extends.

The upper end of each ribbon 9 is curled, or otherwise ofl'set, as indicated at 15. A leaf spring 16, formed of a single leaf or a plurality of juxtaposed leaves 16' secured together by a rivet or any other suitable fastening means, is provided with a slot 17 extending downwardly from the upper edge of the spring to receive ribbon 9 with offset 15 abutting the rear side of the spring. Rib 11 engages the front side of the spring about its center. The lower edge of each spring is curled upwardly, as indicated at 18, and is engaged by a bolt or similar securing element 19 having a curled end 20. A nut 21 threaded on the opposite end of bolt 19 may be tightened to place any desired tension on the upper end of ribbon 9. The curvature of ends 18 and 20 of the spring and bolt prevents slipping of these members relative to each other. The lower ends of adjacent spring 16 terminate at different levels to make nuts 21 more easily accessible.

When the individual screen bars are held under tension and the screen intercepts solids from a stream of liquid flowing through the screen, such solids may strike the screen with suflicient force to tend to flex or distort the screen bars. Any screen bar may flex slightly in the transverse direction by forcing the upper end of spring 16 forwardly, but the spring will immediately return to its normal position and stretch ribbon 9 tautly as soon as the force is discontinued.

While I have described a preferred embodiment of my invention in considerable detail, it will be understood that the description thereof is intended to be illustrative, rather than restrictive, as many details may be modified or changed without departing from the spirit or scope of the invention. Accordingly, I do not desire to be restricted to the exact construction described.

I claim:

1. A tensioning device comprising a leaf spring having one end engageable with the member to be held under tension, a supporting member spaced from said spring, a securing element engageable with the opposite end of the spring and said supporting member to hold said spring and said supporting member in predetermined spaced relationship, and a rib projecting from said supporting member, said rib being engageable with the center portion of said leaf spring.

2. A tensioning device comprising a leaf spring having one end engageable with the member to be held under tension, a bracket spaced forwardly of said spring and having a rearwardly extending projection engaging the center portion of said spring, and a bolt secured to said bracket, the opposite end of said bolt being engageable with the opposite end of said spring, and means for tightening said bolt to force the center of said spring against said projection and exert force against the first mentioned end of said spring to urge it rearwardly.

3. In combination with a screen comprising a plurality of flexible screen bars each secured at one end, a tensioningdevice comprising aplurality of leaf springs each having one end engaging the opposite end of one of said screen bars, a rigid member fixed ina position spaced forwardly of said springs, a projection extending rear- Wardly of said fixed member and engaging the front face of each of said springs, means engaging the opposite end of each of said springs, said last mentioned means being operable to force the last mentioned end of said springs towards said fixed member to force the center of each spring against said projection, thereby exerting force on the first mentioned end of each spring to holdthe ends of said screen bars under tension.

4. In combination with a screen comprising a plurality of flexible screen bars each secured at one end, a tensioning device comprising a plurality of leaf springs each having one end engaging the opposite end of one of said screen bars, a bracket extending transversely of said screen below said screen bars and forwardly of said springs, a projection extending rearwardly of said bracket into engagement with the center portion of each of said springs, bolts secured in said bracket and engaging the opposite ends of said springs, and means to tighten said bolts to force the center of said springs against the projection and to hold the ends of said screen bars under tension.

5. In combination with a screen comprising a plurality of flexible metal strips each secured at one end, said strips extending in parallel relationship, a tensioning device comprising a plurality of leaf springs aligned with said strips in a plane extending at right angles to the plane of said strips, each of said springs having one end engaging an end of one of said strips, means holding the central portion of each of said springs against forward movement, and means exerting force against the opposite end of each of said springs at right angles to the plane of said spring to hold said strips under tension.

References Cited in the file of this patent FOREIGN PATENTS 663,502 Germany Aug; 16, 1938 

